Network security using optical attenuation data

ABSTRACT

A data processing device is connectable to a communication network and operable to receive data associated with an attenuation characteristic of a transmission line of a cable in a cable communication subsystem, the subsystem comprising a transmitter and/or receiver coupled to the cable. The data processing device is responsive to the received data to initiate a security procedure.

BACKGROUND

Networking infrastructures such as data centers house large numbers ofelectronic equipment, such as computers and storage devices. Suchnetworking infrastructures can span from a single room to multiplefloors of an entire building. Servers are often stacked in rack cabinetsthat are placed in rows forming corridors so technicians can access therear of each cabinet. Mainframe computers and other storage devices areoften placed near the servers and can occupy spaces as large as theracks themselves.

Data centers and other networking infrastructures can have enormousnumbers of cable and wires connecting various electronic equipments.Even though such facilities are highly organized, the number of cablesinterconnecting such equipment can be overwhelming. Installing,maintaining, and tracking cables and connections to equipment, andidentifying degradation or failure of specific cable subsystems, can becomplex. Timely identifying changes to network infrastructure thatrepresent potential security related events can be problematic in suchenvironments.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be well understood, various embodimentsthereof will now be described, by way of example only, with reference tothe accompanying drawings, in which:

FIG. 1 is a high level diagram of a communication network, including ahost computer having a physical layer security application;

FIG. 2 shows selected features of a cable end connector connected to acable;

FIG. 3 shows selected features of a network device and of a transceiverconnected to the network device;

FIG. 4 is a functional diagram illustrating control circuitry of atransceiver, including reflectometer control logic;

FIG. 5 shows selected features of the host computer system;

FIG. 6 illustrates an arrangement of computer programs executable on thehost computer system, including a security manager;

FIG. 7 is a table illustrating some cable subsystem operational statesthat are detectable using cable subsystem components having variouslevels of enhancement;

FIG. 8 illustrates a method of applying physical layer security in acommunication network; and

FIG. 9 is a state diagram of an exemplary state machine to implementphysical layer security.

Drawings are schematic and not to scale.

DETAILED DESCRIPTION

In accordance with some embodiments of the invention, a security manageris implemented, for example in software on a data processing device inthe form of a network management server or other host computer. Theexemplary management server is connected to a communication network suchas a data centre, comprising a plurality of cable subsystems. Each cablesubsystem has for example, a cable, respective cable end connectors atopposite ends of the cable, and two transceivers, the cable endconnectors each coupled to a respective one of the transceivers totransmit and receive relatively high frequency and relatively high powercommunication signals through the cable. The transceivers are coupled,for example hot plugged, into respective network devices (examples:switch, controller of a storage device, server host bus adapter (HBA)),to enable the network devices to control the transceivers fortransmitting and receiving signals through the cable.

Also in accordance with some embodiments, the cable end connectors andthe transceivers use relatively low frequency, low power, monitoringand/or diagnostic channels to receive and store data associated with atleast one physical layer characteristic of a cable subsystem in memory,for example in memory on the transceivers, in accordance with a suitableprotocol. Network devices coupled to transceivers include functionalityto access the data stored in the transceiver memory, and to communicatethe data through the network to the network management server, forexample using standard protocols such as SMI-S (Storage ManagementInitiative-Specification) or SNMP (Simple Network Management Protocol).

In at least some embodiments the security manager collects the cablesubsystem physical layer data and assesses the physical layer data todetermine a present operational state, or security state, of cables andtransceivers of a cable subsystem. The accuracy of the determinedoperational state can vary between cable subsystems, depending on thesophistication of cable monitoring features of individual cabletransceivers and connectors. The level of sophistication of physicallayer monitoring and consequential level of accuracy of determination ofoperational state can vary between cable subsystems across the network,and such variations can be accommodated by the security manager. Forexample, in one embodiment an algorithm assesses the physical layer dataand uses stochastic inference to determine an estimate of cable andtransceiver operational state. The security manager also processesevents received from the managed network devices and provides anotification service where required, for example by customer policies.

According to at least some embodiments, the security manager storesdetails of predetermined cable subsystem operating states that representsecurity states requiring initiation of a corresponding predeterminedsecurity procedure. In this manner, the network management server caninitiate an appropriate security procedure in response to receipt of thecable subsystem physical layer data. The definition of which operationalstates represent security states, and/or of which security procedurescorrespond to which specific security states requiring initiation of asecurity procedure, can be at least partially effected by acustomer/user of the data centre or other managed network settingpolicies. Some security procedures may be automatically effected, forexample automatic deactivation of specific cables and/or transceivers.Some security procedures may require at least partial human involvement,for example to confirm a deactivation decision prior to effectingdeactivation, or to authorise reactivation of a cable and/or transceiveron the network. Various embodiments of the invention facilitate networksecurity decisions based on physical layer data, in contrast toinferring physical layer status from higher-level information, forexample from OSI layer 2 frames. At least some embodiments facilitate areal-time security response to network security breaches defined usingcustomer security policies.

In some embodiments, the cable includes multiple transmission lines. Forexample, a multimode fiber optic cable for use in a data centre maycomprise two transmission lines in the form of two optical fibers. Inuse, one fiber is connected to a transmitter optical subassembly of atransceiver, and the other fiber is connected to a receiver opticalsubassembly of the transceiver. Enhanced transceivers are provided thatinclude respective embedded reflectometers, for example in the form ofembedded optical time domain reflectometers (OTDRs). An enhancedtransceiver may detect a reflected test pulse using the receiver opticalsubassembly as a photodetector, by redirecting reflected energy from thetransmitter fiber through an end of the receiver fiber. In alternativeembodiments, the reflected energy is detected using an additionalphotodetector. Enhanced transceivers may also be provided for othertypes of cable, for example single mode and/or single fiber cable,and/or electrical communication cable.

Data collected by the OTDR is stored, for example in a memory of thetransceiver provided for storing OTDR data, and processed to obtain anattenuation characteristic indicative of the rate of attenuation of thereflected signal relative to distance along the optical fiber.Processing of the data can occur in circuitry on board the transceiverand/or maybe transmitted to another device for processing. The resultsof the processing are stored in a memory on the transceiver, oralternatively on the network device hosting the transceiver, and madeavailable to the security manager. The security manager can compareupdated OTDR attenuation characteristic data with historical OTDRattenuation characteristic data to determine whether a significantincrease in attenuation has appeared at any specific location along theoptical fiber since the last update. This determination is used todetermine a present security state, and a corresponding securityprocedure may be initiated taking into account the potential tap to theoptical fiber.

At least some embodiments of the invention facilitate the provision of aconvenient and cost-effective transmission line tap monitor service. Theprovision of indications relating to breaks in or degradation oftransmission lines can also be facilitated. The level of sophisticationof reflectometer components required to identify major attenuationanomalies indicative of many types of optical tap, for example a tapimplemented using an adapter and tapping, say, 50% of signal energy, isavailable at relatively modest cost, sufficient to enable cost-effectiveembedding of reflectometers in transceivers.

FIG. 1 illustrates an exemplary communication network 100, for example adata communication network in the form of a data centre comprising highthroughput fiber optic communication cables and devices, althoughembodiments of the invention are applicable to any communicationnetwork. The network comprises a director switch 110, network switches111, 112, storage arrays 113, 114, a tape library 115, a patch panel116, servers 117, 118, 119, and a host computer system 120 such as anetwork management server to execute a physical layer securityapplication 121.

Cables 130 to 141 are shown interconnecting various ones of the networkdevices 110 to 120. Opposite ends of the cables 130 to 141 areterminated using cable end connectors. At least some of the endconnectors are active end connectors such as the end connector 200 ofFIG. 2, which comprises memory 210 for storing data relating to physicallayer characteristics of a cable subsystem and a communication interface220 for communicating with a transmitter and/or receiver to provide arelatively low frequency and low power diagnostic and/or monitoringchannel. The data can be stored and accessed, for example according tothe SFF-8472 Specification for Diagnostic Monitoring Interface forOptical Transceivers, extended as necessary to accommodate the desireddata physical layer parameters, or any other suitable protocol. The endconnector 200 represents an LC connector, and the cable 201 comprises,for example, two transmission lines in the form of respective multimodeoptical fibers 203, 204. However, in alternative embodiments any othercable end connector type and appropriate corresponding cable type(including single mode optical fiber cables and electrical communicationcables), suitable for use in a communication network, can be employed.

Active network devices such as the switches 111, 112, storage arrays113, 114, tape library 115 and servers/hosts 117 to 120 are operable totransmit and/or receive communication signals through the network usingtransmitters and/or receivers. An exemplary network device 300 is shownin FIG. 3, having an exemplary transceiver 350 connected thereto. Thetransceiver 350 shown in FIG. 3 represents an SFP (Small Form-factorPluggable), SFP+, or SFF optical transceiver. However, in alternativeembodiments any other transceiver, transmitter or receiver type suitablefor use in a communication network can be employed, including those forconnecting to electrical communication cables. The transceiver 350includes a memory 360 for storing, for example according to SFF-8472,data relating to physical layer characteristics of a cable subsystem200, 201, 350, and a communication interface 370 for communicating witha cable end connector 200 over the relatively low frequency and lowpower diagnostic and/or monitoring channel.

The exemplary network device 300 comprises a processor 301 a memory 302and an external communication interface 303. The memory 302 storescomputer program instructions 304, for example in the form of softwareand/or firmware, to provide at least some of the functionality of thenetwork device. The network device 300 is operable to read the physicallayer data stored in the transceiver memory 360. Communication betweenthe network device 300 and the transceiver 350 can be effected, forexample, using an inter-integrated circuit communication protocol suchas I2C. The received physical layer data 305 can be stored, for exampleaccording to SFF-8472, in network device memory 302, and communicated tothe physical layer security application 121 on the host computer 120over the network 100 by the external communication interface 303 usingany appropriate protocol, for example, SMI-S (Storage ManagementInitiative-Specification) or SNMP (Simple Network Management Protocol).

Where the network device 300 comprises a switch 111, 112, the switchsoftware stack supports extended MIB (management information base) andCIMOM (common information model object manager) and provides SMI-S andSNMP functionality for communicating the data 305 over the network 100.Where the network device 300 comprises a storage controller, such as adisc array 113, 114 controller or tape library 115 controller, thestorage controller software stack supports extended MIB and CIMOM andprovides SMI-S and SNMP functionality for communicating the data 305over the network 100. A network device 300 comprising a host computersuch as a server 117 to 120 includes a network interface controller(example: Fibre Channel host bus adapter) having firmware to supportreading extended physical layer data from the transceiver 350, and thehost computer software stack includes a network interface controllerdriver also supporting reading the extended physical layer data 305, andprovides SMI-S and SNMP functionality for communicating the data 305over the network 100.

In one embodiment, the transceiver 350 comprises an integrated circuit(IC) device 351 that provides the memory 360 and the communicationinterface 370. The transceiver IC device 351 in some embodimentscomprises a very low power IC tag device. The exemplary transceiverincludes electrical contacts 371 to mate with corresponding electricalcontacts 271 of the connector 200. The transceiver electrical contacts371 extend between the communication interface 370 and one of therecesses 355, 356, which recesses receive respective ends 235, 236 ofthe cable end connector 200 to mate optical fibers 203 of the cable endconnector 200 with respective optical components of a transmitteroptical subassembly 357 and a receiver optical subassembly 358 of thetransceiver 350. The transceiver also comprises a communicationinterface (451, FIG. 4) to communicate with the network device 300.

The cable end connector 200 comprises an IC device 251 that provides thememory 210 and the communication interface 220. The connector IC device251 in some embodiments comprises a very low power IC tag device. Theelectrical contacts 271 of the connector 200 extend between thecommunication interface 220 towards a front end portion of the connector200 to mate electrically with the transceiver electrical contacts 371when the connector 200 is received in the transceiver 350. A connectorengagement detection mechanism (not shown) may be provided to provideinformation regarding connector/transceiver engagement state, forexample whether a connector is fully engaged, partially engaged or notengaged with a transceiver.

The transceiver 350 and/or the connector 200 can include a visualindicator (not shown) for indicating operational states of the cablesubsystem. For example, light from an LED (not shown) controlled by thetransceiver IC device 351 can be channeled by a light pipe through thetransceiver to an externally accessible region of the transceiver 350and, when a connector 200 is connected to the transceiver, channeled bya further light pipe of the connector 200 through portions of theconnector to a user visible region of the connector.

Communication between the connector IC device communication interface220 and the transceiver IC device communication interface 370 over theelectrical contacts 271, 371 can be by any convenient inter-integratedcircuit protocol, and the IC devices 251, 351 can be arranged toautomatically transfer or exchange physical layer characteristic datastored in the memories 210, 360. In some embodiments, further electricalcontacts 280, 380 can be provided on the connector 200 and thetransceiver 350 to provide low level electrical power from thetransceiver IC device 351 to the connector IC device 251 when theconnector 200 is engaged with the transceiver 350. In alternativeembodiments, the transceiver communication interface 370 can take theform of an RFID reader, and the connector IC device 251 can take theform of an RFID tag having a communication interface 220 in the form ofan RFID transponder with parasitic power supply, to transfer databetween the connector 200 and the transceiver 350, for example asdisclosed in US 2008/0240724A1 which is incorporated herein by referencein its entirety. In some embodiments, RFID transponders respectivelyassociated with a connector and transceiver are adapted to communicatewith one another to allow information from each of the transponders tobe communicated to an RFID reader via communication with only onetransponder, as disclosed in US2008/0100456A1, which is incorporatedherein by reference in its entirety, and from the RFID reader to thesecurity application 121.

FIG. 4 shows circuitry of the transceiver 350, supported for example ona circuit board 390 of the transceiver 350. The transceiver 350comprises a transmission control channel including an electricaltransmitter control connection 405, equalisation circuitry 406 and alight source driver 407 for controlling a light source 408, for examplea transmitter optical subassembly comprising a laser diode or VCSEL. Thetransceiver 350 also comprises a receiver control channel including aTIA (transimpedance amplifier) 422 to receive signals from a receiveroptical subassembly 419 including for example a laser diode, limitercircuitry 421 and an electrical connection 420. Controller logic 401implements various functions of the transceiver 350. The transceivercircuitry implements an inter-integrated circuit interface 451, forexample an I2C interface, to enable access to the memory 360, forexample by a network device 300 hosting the transceiver 350.

The exemplary transceiver 350 comprises a first enhancement in the formof a low-frequency diagnostic side band communication channel providedby a modulator 410 in the transmission control channel, a demodulator411 in the receiver control channel, and modulation control logic 412.In one embodiment, the side band communication channel can beimplemented, for example, as disclosed in co-pending U.S. patentapplication Ser. No. 12/241,945. The side band communication channelenables cable subsystem physical layer characteristic data to becommunicated between enhanced transceivers 350 at opposite ends of acable, to facilitate collection of complete cable subsystem physicallayer data at both ends of a cable.

The exemplary transceiver 350 comprises a second enhancement comprisingan embedded reflectometer in the form of an OTDR (optical time domainreflectometer) including control logic 430 and OTDR memory 431. The OTDRlogic operates to close normal transmissions through the transmissioncontrol channel and receive control channel, using switches 435, 436,and causes the laser 408 to send a test pulse through the transmissionfiber channel to obtain attenuation data in respect of the transmissioncable. In one embodiment, the OTDR control logic 430 controls a lightvalve 439 to enable reflections of the test pulse from the opticaltransmission fiber to be channeled to the receiver optical subassembly419 through the optical receiver fiber channel, as described inco-pending PCT patent application number PCT/US2009/062709, which isincorporated herein in its entirety. Alternatively, a further lightdetector can be provided for receiving OTDR reflections from thetransmission fiber. The digitally sampled signals resulting fromdetection of the OTDR test pulse reflections can be stored in OTDRmemory 402. The sampled signals can be processed on board thetransceiver 390, or transferred to another device, for example thetransceiver's host network device, for processing. The attenuationpattern resulting from the processing of the OTDR data should besufficiently accurate to indicate whether, for example, an optical taphas been placed on a cable, for example using a cable adapter, and toapproximately identify the distance of the tap location along the cable,even using components of relatively modest sensitivity and cost. For adual fiber cable, OTDR data can be obtained for the receiver fiberchannel from a transceiver 350 with the second enhancement at anopposite end of the cable, using the side band communication channel.

Various cable subsystem physical layer characteristic data can be storedin the memory 210 on the cable end connector 200 and in the memory 360of the transceiver 350. Cable data parameters stored in the connectormemory 210 and transceiver data parameters stored in the transceivermemory 360 can be transmitted between the memories 210, 360 and storedin both memories 210, 360. Furthermore, cable data parameters andtransceiver data parameters can be received from a connector 200 andtransceiver 350 at an opposite end of the cable using the sidebandcommunication enhancement, and also stored in the transceiver memory 360and the connector memory 210. Storage of data in the connector memory210 can provide convenient access to the data in certain circumstances,for example to enable convenient access to the data by a handheld RFIDreader. In some embodiments, a transceiver (not shown) is provided thatomits the modulated sideband first enhancement and/or the OTDR secondenhancement.

In at least some embodiments, variously stored cable subsystemparameters relate to identifiers of cables, connectors, andtransceivers, and/or to present quality of cable subsystem communicationperformance. Cable parameters can include, for example, at least one ofthe following non-limiting exemplary cable parameters: cable serialnumber; connector type, cable type manufacturer identification,manufacturer's data, cable performance parameters such as attenuationcharacteristics during installation. Transceiver parameters can include,for example, at least one of the following nonlimiting exemplarytransceiver parameters: transceiver identifier, laser transmitteroptical power, laser transmitter current, photodiode receiver opticalenergy. OTDR data, for example data indicating a possible optical tap,is also stored in the transceiver memory 360 and the connector memory210. In some embodiments relating to electrical communication cables,analogous electrical cable parameters can be provided corresponding tosome of the optical-specific parameters mentioned above, includingelectrical TDR data.

FIG. 5 illustrates an exemplary system 500 to execute the physical layersecurity application 121. The system includes provision for calculatingduring use the operational condition of a cable system comprisingmultiple cable subsystems, and to initiate security proceduresresponsive to received cable subsystem physical layer characteristicdata. The system 500 includes a host computer system 120 and arepository, warehouse, or database 530. The host computer system 420comprises a processing unit 450 (such as one more processors or centralprocessing units, CPUs) for controlling the overall operation of memory460, for example RAM (random access memory) for temporary data storageand ROM (read-only memory) for permanent data storage. The memory storesprogram instructions 470 for implementing a security manager (610, FIG.6) and other security related applications. The processing unit 450communicates with memory 460, database 530, security manager 610 andmany other components via buses 490. The program instructions 470 mayalso implement a cable monitoring and diagnostic system (not shown).Embodiments in accordance with the invention are not limited to anyparticular type or number of databases and/or host computer systems.Exemplary host computer systems include, but are not limited to,computers (portable and nonportable), servers, mainframe computers,distributed computing devices, laptops, and other electronic devices andsystems whether such devices and systems are portable or nonportable.

FIG. 6 shows the interaction of various applications 600 implemented bythe computer instructions 470 of the host computer system 120 shown inFIG. 5, including a security manager 610. In the present embodiment, thesecurity manager 610 is operable to receive data associated with variousphysical layer characteristics of at least one cable communicationsubsystem. That is, the security manager 610 receives, for example froma network device over the network 100 using SNMP or SMI-S, data such astransceiver operational parameters from both ends of a cable subsystem,OTDR generated data regarding potential optical fiber taps, and cableidentification and performance parameters.

Conveniently, the security manager is implemented using a securityservice module 611 and a security procedure module 612. The securityservice 611 executes for example, data collection and event processingfrom managed network devices. Some security related data may be obtainedby polling managed network devices at frequencies appropriate to theperceived security threats. Other security related data may be obtainedusing events triggered by the managed network devices, for example if anembedded OTDR detects a potential optical tap in a fiber optic cable.The security service 611 determines (including in some embodiments bystochastic inference) a security state for a cable subsystem, using thereceived physical layer data and stored predefined possible states. Thesecurity service 611 provides the presently determined security state tothe security procedure module 612. The security service 611 alsoprovides external notification 613, for example to a networkadministrator, where required.

Security configuration data is stored, for example in the database 530,for maintaining and implementing received customer security policies,and can include security procedure algorithms. The security proceduremodule 612 is arranged to receive a presently determined security statefrom the security service 611 and to determine an appropriate securityprocedure in accordance with the received security state and the storedsecurity configuration data. The security procedure module 612 is alsoarranged to output information for the customer relating to any securityprocedure initiated by the security manager 610 in response to asecurity state. The security procedure manager 612 may also be arrangedto output information to the security service 611, for example toinitiate a security related action by a managed device, and/or totrigger a notification or logging action by the security service 611.

The exemplary program instructions 470 also implement a security policywizard application 621 and an API (application programming interface)620 to facilitate input of customer policies to the security module 612.Other applications may also be implemented and communicate with thesecurity manager 610 through the API 620, for example a command lineinterface application 622, host application 623 (example: data centremanagement application) and/or web services application 624.

The exemplary network 100 of FIG. 1 can accommodate cable subsystemswhich vary widely as to the range of physical layer data they are ableto provide for cable security, monitoring and diagnosis. Accordingly,the accuracy with which operational states and security states can beassessed can vary widely between network devices. It is envisaged thatnetwork administrators will select transceivers and cables with thevarious enhancements described above for network connections whereimproved accuracy and security is desired. Different respective securitypolicies can be set for different respective cable subsystems.

The table of FIG. 7 lists in the left-hand column various possible cablesubsystem operating conditions or detectable events that can be used todefine security states, and along the top row various levels of abilityto provide various data associated with physical layer characteristicsof a cable communication subsystem. The ability to provide a variedrange of data is related to the degree of enhancement of thetransceiver(s) and/or cable end connectors of a cable subsystem. Marksin the boxes of the table of FIG. 7 indicate whether a specificoperating condition can be determined using a specific level of abilityto provide physical layer data. All columns in FIG. 7 represent a cablesubsystem, or network of cable subsystems, including at least onetransceiver that is capable of collecting physical layer data intransceiver memory for access by a network device hosting thetransceiver, the network device being operable to access the data andfurther communicate the data to a physical layer security application121.

Column 1 in FIG. 7 represents the use of a cable subsystem, or networkof cable subsystems, having a transceiver that is capable of collectingin transceiver memory data relating to a present quality ofcommunication performance of the transceiver. Such data can comprise,for example, transmitter power and/or transmitter current parameters,photodiode receiver energy parameters. Column 1 does not necessarilyrelate to cable subsystems having enhanced side band communication orcable tap detection capability. However, provided that the networkdevices 300 hosting column 1 transceivers at each end of the cablesupport receiving physical layer data 305 from the transceiver andcommunicating the data to the physical layer security application 121,the security application 121 can obtain the physical layer data fromboth ends of the cable subsystem. It can be seen from FIG. 7 that column1 cable subsystems can enable a physical layer security application 121to detect (including infer) that a cable is disconnected andreconnected, and also that the cable is disconnected or broken, bypiecing together the quality of communication performance data from bothends of the cable. The security application 121 can in some embodimentsenable a network user or administrator to select an identified multicable link, or route, between network devices, the link comprisingvarious cable subsystems, and monitor the constituent cable subsystemsof the link to identify any cable connection topology changes involvingthe link, employing various detectable operating conditions as required,for example the cable disconnected and reconnected condition and/or thecable replaced condition.

Column 2 in FIG. 7 represents a cable subsystem, or network of cablesubsystems, using transceivers at both ends of the cable that supportside channel communications, for example an accordance with the firstenhancement described above. Because transceivers at both ends of thecable subsystem store physical layer data relating to the transceiver atthe opposite end of the cable subsystem, including transceiver identitydata, if one of the transceivers is swapped for a transceiver having adifferent identity, or no side channel communication capability, thesecurity application 121 can detect the transceiver swap by comparinghistorical and present transceiver identity data stored at the remainingtransceiver. The column 2 arrangement can also be used to detect cabledisconnection and reconnection, and cable disconnected or broken, asdescribed above in connection with the column 1 arrangement.

Column 3 in FIG. 7 represents the use of cable end connectors andcorresponding transceivers modified to detect and engagement state ofthe connector in the transceiver, for example no engagement, partialengagement, or full engagement, and supplied the engagement state datato the transceiver memory. The security application 121 can use thestored data to detect a connector partially engaged condition.

Column 4 in FIG. 7 represents cable subsystems that use cable endconnectors and transceivers that can bring together physical layer datafrom cable end connectors and their respective interconnectedtransceivers. For example, column 4 end connectors and transceivers mayexchange physical layer data when interconnected, such as in response tothe interconnection of respective IC devices 251, 351 by means, forexample, of electrical contacts or RFID connection. The column 4arrangement permits detection when a cable storing identity informationis replaced with another cable having a different identity, or noidentity, by comparing a present cable identity stored in transceivermemory with a previously stored cable identity. Column 4 cablesubsystems can also in most circumstances enable a physical layersecurity application 121 to detect that a cable is disconnected andreconnected, and that the cable is disconnected or broken.

Column 5 in FIG. 7 represents the use of transceivers with cable tapdetection capability, for example using transceivers with embedded OTDRcapability, in accordance with the second enhancement described above.OTDR data from the transceiver can be used by the security application121 to detect cable taps.

FIG. 8 is a flow diagram illustrating a method of applying physicallayer security in the communication network 100 comprising a transceiver350 coupled to a host network device 300, and at least one cable 201coupled to the transceiver 350 to communicate with another networkdevice 300. In step 801, data is obtained relating to an attenuationcharacteristic of a transmission line, for example an optical fiber orelectrical communication cable, of a cable presently connected to atransceiver 350 having an embedded reflectometer. In step 802 the datais processed, and in step 803 a security procedure is automaticallyinitiated if required based on results of the processing. At least someof the data, may, for example, be received and stored in a memory 210and/or 360 and/or 302.

In at least some method embodiments according to the invention, thesecurity manager 610 receives data including: transceiver communicationinput/output parameters (transmitter optical power and current, opticalreceiver energy), transceiver identifiers (example: serial numbers) andconnector engagement status (not engaged, partially engaged, fullyengaged) from both ends of a cable subsystem, cable identification andperformance parameters, and the OTDR-generated data. The data iscollected for example from a network device 300 through the network 100,for example over a cable or wireless link using SNMP or SMI-S, bypolling the network device 300 to provide data from the memories 360 ofall its transceivers 350, or from a specifically identified transceiver.OTDR-generated data regarding the presence of potential optical fibertaps, and other potentially time sensitive data, can also be received byvirtue of events notified by a managed network device 300. The securitymanager 610 determines a security state based on the received data, anddetermines an appropriate security procedure in accordance with thereceived security state, stored customer security policies and storedsecurity procedure algorithms. The security manager 610 initiates theappropriate security procedure. For example, a managed network device300 may be required to disable a cable subsystem communication link inresponse to detection of unplugging of a cable from a transceiver. Thesecurity manager 610 can send notifications to a network administratorand/or data centre customer to inform them of the security procedure,and of any further action that might be required to permit reconnectionto the affected cable subsystem of the unplugged cable or another cable.The security manager 610 can also cause a transceiver 350 to control itsLED to visually display a security status.

In one embodiment, the security manager 610 may comprise a state machine900 according to the state diagram illustrated in FIG. 9. The exemplaryMoore state machine 900 comprises the following states:

U Idle

V Security issue relating to fiberW Administrator stateX Security issue relating to transceiverY Security issue relating to connector

Z Reset

The exemplary state machine 900 and further comprises the followingpossible inputs, the inputs representing various detectable operatingconditions that may be indicative of a security breach:

A No optical power detected in both fibersB No optical power detected in one fiberC Connector engagement problemD Cable serial number different to previously stored serial numberE Cable connection and/or disconnection problemF Transceiver serial number different to previously stored serial numberG Tap detected in cable

R Reset

As seen in FIG. 9, from the start 910 any input results in transition tothe Admin state 911, from which date any input results in transition tothe Idle state U. In the Idle state U, a negation of any of thepermissible inputs results in a return to Idle U. In Idle receipt of aninput C, D or E results in a transition to the Connector state Y,receipt of an input capital A, B or G results in a transition to theFiber state V, and receipt of an input capital F results in a transitionto the Transceiver state X. Receipt of inputs A, B or G in the connectorstate Y or in the transceiver state X results in a transition to theFiber state V. Receipt of inputs C, D or E in the Fiber state V or inthe transceiver state X results in a transition to the Connector stateY. Receipt of input F in the Fiber state V or in the Connector state Yresults in a transition to the Transceiver state X.

The Reset R input can be arranged to occur automatically in theConnector state Y, the Fiber state V or the Transceiver state X, andresults in a transition to the Reset state Z. The Reset R input can bearranged to provide notification, logging, link disablement, LED visualstatus indication and clearing of errors, and to require manual input insome circumstances. A Reset R input in the Reset state Z can be used toreturn the state machine to Idle.

In at least some embodiments of the invention, the provision of a realtime transmission line tap monitor and response service is facilitated.At least some embodiments of the invention facilitate the provision of atransmission line breakage and/or degradation indication service.

In at least some embodiments, a network physical layer security systemis provided that can use polling, exceptions and traps, according to thedesired protocol, to gather communication transceiver-based, for exampleSFP+ based, diagnostic information from a network device hosting thetransceiver. The gathered data may be stored in a centralised ordistributed network database. Real-time, or near real-time securityresponses may be provided by the system. A communication cable subsystemcan have many different combinations of operating conditions for itsdifferent elements. The physical layer security system facilitatesdefinition of which operating conditions constitute a possible breach ofsecurity, and what action should be taken in response to an identifiedsecurity breach. For example, depending on a level of severity accordedto specific security breaches, the application could for example send ane-mail notification to a network administrator and/or user, storedetails of the event in a log, or shut down one or more cable subsystemsin an affected link.

As used herein an SFP or small form-factor pluggable is an opticaltransceiver used in optical communications for telecommunication and/ordata communications. SFPs (including SFP+) interface network devices tofiber optic cable. Real time means that the time taken to initiate anaction such as a security procedure is sufficiently short to beperceived by a human user, such as a network administrator, as adequateto enable a timely and appropriate response consequent to the action,and can vary depending on the requirements surrounding different typesof actions. In at least one exemplary embodiment, one or more stepsdiscussed herein are automated, in other words, occur automatically. Asused herein, the terms “automated” or “automatically” (and likevariations thereof) mean controlled operation of an apparatus, systemand/or process using computers and/or mechanical/electrical deviceswithout the necessity of human intervention, observation, effort and/ordecision.

Methods in accordance with exemplary embodiments of the presentinvention are provided as examples and should not be construed to limitother embodiments within the scope of the invention. For instance,blocks in diagrams or numbers (such as (1), (2), etc.) should not beconstrued as steps that must proceed in a particular order. Additionalblocks/steps may be added, some blocks/steps removed, or the order ofthe blocks/steps altered and still be within the scope of the invention.Further, specific numerical data values (such as specific quantities,numbers, categories, etc.) or other specific information should beinterpreted as illustrative for discussing exemplary embodiments. Suchspecific information is not provided to limit the invention.

The above discussion is meant to be illustrative of the principles andvarious embodiments of the present invention. Numerous variations andmodifications will become apparent to those skilled in the art once theabove disclosure is fully appreciated. It is intended that the followingclaims be interpreted to embrace all such variations and modifications.

1. A data processing device connectable to a communication network andoperable to: receive data associated with an attenuation characteristicof a transmission line of a cable in a cable communication subsystem,the subsystem comprising a transmitter and/or receiver coupled to thecable; and responsive to the received data, initiate a securityprocedure.
 2. The data processing device of claim 1, further operable toreceive further physical layer characteristic data relating to at leastone transmitter and/or receiver connected to at least one end of thecable, the data comprising at least one selected from: transmitterpower; transmitter current; photodiode receiver optical energy; atransmitter and/or receiver identifier; an identifier of a cableconnected to the transmitter and/or receiver, and initiate a securityprocedure responsive to the received data.
 3. The data processing deviceof claim 1, wherein the cable comprises a dual optical fiber cableconnected at opposite ends to respective fiber optic transceivers, andthe data is obtained for each respective optical fiber of the cable froma respective one of the transceivers.
 4. The data processing device ofclaim 1, wherein the received data is indicative of a break in ordegradation of an optical fiber of a said cable, or of an optical tapapplied to a said fiber.
 5. The data processing device of claim 1,operable to initiate a said security procedure in respect of a saidcable and/or in respect of the transmitter and/or receiver.
 6. The dataprocessing device of claim 1, wherein the security procedure includes areconnection process prior to permitting active reconnection of adisconnected cable to a said network transmitter and/or receiver.
 7. Thedata processing device of claim 1, operable to use the received data todetermine a present predetermined security state of the at least onecable subsystem, and determine a predetermined security procedurecorresponding to the security state.
 8. The data processing device ofclaim 1, comprising a management server having program instructionsstored in memory to cause the server to automatically respond to thereceived data by initiating the security procedure.
 9. The dataprocessing device of claim 1, operable, from time to time, to receiveand store the data associated with a transmission line attenuationcharacteristic, and to respond to the data using both the most recentlystored and the previously stored data.
 10. The data processing device ofclaim 1, wherein the transmitter and/or receiver and the at least onecable respectively comprise a fiber optic transmitter and/or receiverand at least one fiber optic cable.
 11. The data processing device ofclaim 1, further comprising an interface to enable receipt of securitypolicies to define predetermined security states based on the receivedattenuation-related data and/or to define corresponding responsivesecurity procedures.
 12. A tangible computer readable medium bearingcomputer program instructions to cause a processor to use dataassociated with an embedded reflectometer of a cable communicationsubsystem, the subsystem comprising a transceiver and at least onecable, to detect in real time a predetermined physical layer securitystate of the subsystem, and initiate a predetermined correspondingresponse.
 13. The tangible computer readable medium of claim 12, whereinthe security state and/or the response is predefined by a user of thenetwork.
 14. A method of applying physical layer security in acommunication network comprising a transceiver coupled to a host networkdevice, and at least one cable coupled to the transceiver to communicatewith another network device, the method comprising: obtaining datarelating to an attenuation characteristic of a transmission line of acable presently connected to a transceiver having an embeddedreflectometer; processing the data and automatically initiating asecurity procedure if required based on results of the processing. 15.The method of claim 14, wherein the data, or a result of processing thedata, is stored in a memory of the transceiver, and the stored data iscommunicated to another device to perform at least part of theprocessing.
 16. The method of claim 14, wherein the data, or a result ofprocessing the data, is indicative of a break in or degradation of thetransmission line, or of an optical tap applied to the transmissionline.
 17. The method of claim 14, comprising obtaining the data using anOTDR device embedded in the transceiver, communicating the data throughthe network from the host device to a physical layer security manager toperform the processing.
 18. The method of claim 14, comprising providinga real time transmission line tap monitor and response service.
 19. Themethod of claim 14, wherein the characteristic data includes dataobtained by transceivers at both ends of the cable.
 20. The method ofclaim 14, comprising automatically initiating a security procedure todisable a communication link including the cable.